1. Any permanent that leaves the battlefield and reenters is an entirely new permanent with no memory or connection of its last appearance so it won't have any abilities.
2. Those are all legal choice though they won't do anything in the case of Awaken/Poisonous. For a full list of legal choices see https://mtg.gamepedia.com/Keyword_ability
Edit: As MadMageQc mentions in the update for unstable you are allowed to pick an N for anything that has been printed on a creature before so you can choose Poisonous 1 or Anialotor 3 for example, but not Poisonous 300. Awaken would sill effectively so nothing.
3. Since this is a silver border card this one isn't really covered by rules, but it would make most sense if it was in 5 seconds of being put on the stack.
Disclaimer : The only “official” document we have for rulings on Unstable cards is the FAQAWASLFAQPAFTIDAWABIAJTBT published by Mark Rosewater. Beyond that, all answers are interpretation and of course, your playgroup should rule things as they see fit. For “official” confirmation on any questions beyond what’s there, you’ll have to contact Rosewater via his blog or otherwise.
1. The abilities that it has are only the ones granted to the current incarnation on the battlefield by that incsrnation's own ability. If it leaves and returns, it has become a new object, so it doesn’t have those keywords. Of course, you’re still barred from naming those, so to sum it up, blinking it is no bueno.
2. Awaken and Totem Armor were never printed on creature cards, so no. Poisonous is less clear, but since Virulent Sliver doesn’t directly have the keyword but rather grants it to itself, logically, it can’t be chosen either, same as why Cairn Wanderer won’t get flying from a Winged Sliver in the graveyard. EDIT @genini2 : You seem to have missed the "printed on a creature card" part.EDIT 2 : I was off there, my bad.
3. This is more unclear as to what would be in MaRo’s head about this, that may be worth asking him, but normally, triggered abilities shouldn’t have anything named for them until they resolve. Now, players being unclear about whether the ability is on the stack of course isn’t ideal. Crystal Clear communication seems paramount here: the way I’d rule it out is, Monstrosity’s controller must say the ability is on the stack ASAP after the spell triggering it is cast, then ask whether it resolves, and has 5 seconds from the moment they’ve been told that it does. EDIT : The ability has an 'intervening if' clause, which makes it nonsensical within the normal rules but supports genini2's intepretation above. So I'd say the Monstrosity's controller must say the ability triggers ASAP after the spell and then has 5 seconds right after aknowledging the ability, in the same breath with no priority pass and no interruption possible. Any Stifle would be cast after the choice is made (for what that's worth).
EDIT:
Quote from genini2 »
2. Those are all legal choice though they won't do anything in the case of Awaken/Poisonous.
Not that it matters for those two, but for others that do appear on creature cards, actually, according to Rosewater, you can pick a modifier, but you have to pick one that got printed on a creature card.
Quote from Unstable FAQAWASLFAQPAFTIDAWABIAJTBT »
You may choose any keyword ability that appears on any printed Magic creature card. You can't pick keyword actions like explore or scry. If the keyword has a modifier, such as a mana cost or a number, you must choose a modifier that's been printed. Sorry, "annihilator 500" fans.
I'm a former judge (lapsed), who keeps up to date on rules and policy. Keep in mind that judges' answers aren't necessarily more valid than those of people who aren't judges; what matters is we can quote the rules to back up our answers. When in doubt, ask for such quotes.
Yeah, thinking about it more, those do have the keywords printed on them and, by the same token, Virulent Sliver has Poisonous 1 printed on it (you're stuck with 1 as the number on Poisonous, though, see above). My reasoning with comparing to Cairn Wanderer doesn't hold, there is a difference between having a keyword ability and having the keyword printed on the card. Editing my post above further... Sorry about all the back and forth, but we're talking interpretation of a silver-bordered card, so I won't be too hard on myself.
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I'm a former judge (lapsed), who keeps up to date on rules and policy. Keep in mind that judges' answers aren't necessarily more valid than those of people who aren't judges; what matters is we can quote the rules to back up our answers. When in doubt, ask for such quotes.
2. Are abilities like awaken, totem armor and poisonous legal choices?
3. When does the 5 second countdown start? As soon as the ability is put onto stack or when it tries to resolve?
Ty in advance.
2. Those are all legal choice
though they won't do anything in the case of Awaken/Poisonous. For a full list of legal choices see https://mtg.gamepedia.com/Keyword_abilityEdit: As MadMageQc mentions in the update for unstable you are allowed to pick an N for anything that has been printed on a creature before so you can choose Poisonous 1 or Anialotor 3 for example, but not Poisonous 300. Awaken would sill effectively so nothing.
3. Since this is a silver border card this one isn't really covered by rules, but it would make most sense if it was in 5 seconds of being put on the stack.
1. The abilities that it has are only the ones granted to the current incarnation on the battlefield by that incsrnation's own ability. If it leaves and returns, it has become a new object, so it doesn’t have those keywords. Of course, you’re still barred from naming those, so to sum it up, blinking it is no bueno.
2. Awaken and Totem Armor were never printed on creature cards, so no. Poisonous is less clear, but since Virulent Sliver doesn’t directly have the keyword but rather grants it to itself, logically, it can’t be chosen either, same as why Cairn Wanderer won’t get flying from a Winged Sliver in the graveyard. EDIT @genini2 : You seem to have missed the "printed on a creature card" part.EDIT 2 : I was off there, my bad.3. This is more unclear as to what would be in MaRo’s head about this, that may be worth asking him, but normally,
triggered abilities shouldn’t have anything named for them until they resolve. Now, players being unclear about whether the ability is on the stack of course isn’t ideal. Crystal Clear communication seems paramount here: the way I’d rule it out is, Monstrosity’s controller must say the ability is on the stack ASAP after the spell triggering it is cast,then ask whether it resolves, and has 5 seconds from the moment they’ve been told that it does. EDIT : The ability has an 'intervening if' clause, which makes it nonsensical within the normal rules but supports genini2's intepretation above. So I'd say the Monstrosity's controller must say the ability triggers ASAP after the spell and then has 5 seconds right after aknowledging the ability, in the same breath with no priority pass and no interruption possible. Any Stifle would be cast after the choice is made (for what that's worth).EDIT:
Not that it matters for those two, but for others that do appear on creature cards,actually, according to Rosewater, you can pick a modifier, but you have to pick one that got printed on a creature card.There is Halimar Tidecaller and Umbra Mystic.
Other abusable effects? True-Name Nemesis protection looks cool too. Lol
Warning issued for off-topic discussion. Locking the thread to avoid it going further into "what cool keywords can we name". Also , card tags added.